Despite your points above, C* has 6 regiments on Terra and 12 WarShips in system. They would not weaken that defence one jot on the face of FWLM assaults nearby, they cannot afford to. They have an agreement with the FRR for troops and could pull them back, ut with the Clans getting aggressive, they will likely stay there.
Terra is a frenzy of activity. Titan is coming fully on line and the factories on Terra are running all out. ComStar plans on rebuilding, but has a long way to go and cannot afford to antagonise any great power any further. They have pulled their heads in and wont get adventurous until the new fleet begins launching and the Guards grow some.
Thomas's actions were a direct tit-for-tat retaliation for Gibson. He hit only with WarShips, which sent a signal without descending into all out war.